1. Field of the Invention
The present invention is generally directed to a surface covering product. More specifically, the present invention is directed to a floor covering product having a precoated film wearlayer in which the gloss level of the coating is controlled.
2. Description of the Related Art
Surface covering products, such as floor tiles and floor covering sheets, are well known in the art. The "gloss," or shine, of the floor covering product is commercially significant since differing gloss levels in floor covering products are desired by the consumer. Accordingly, it is known that gloss control can be accomplished through various processes, including by altering the specific coating composition for the amount of gloss desired on the end product, and by controlling the curing of the coating.
A floor covering sheet is frequently manufactured on a belt or drum line, where a substrate is laminated with a transparent covering, or "wearlayer," such that the end product can withstand foot traffic. The wearlayer may be embossed, and if embossed the embossing is done simultaneously with or after the lamination. The wearlayer can be a coated or uncoated film such as a rigid film comprised of polyvinyl chloride (PVC), polyethyleneterephthalate (PET), or glycolated polyethyleneterephthalate (PETG). "Rigid film" is a term of art which means any film that is substantially free of plasticizers, e.g. phthalate esters, thereby imparting resistance of the polymer to deform. Other floor products are coated or covered with the wearlayer, which is typically comprised of a curable composition, such as acrylated urethane or acrylated polyethylene, and is coated in liquid or flowable form onto a vinyl or nonvinyl composition substrate. The wearlayer typically is then cured to form the durable covering to withstand repeated contact in use.
U.S. Pat. No. 4,313,969 to Matthews shows a prior method and apparatus for providing low gloss and gloss controlled radiation cured coating. Matthews discloses a filtered mercury bulb to control spectral distributions. Thus, the gloss control is particularly achieved by varying spectral distribution in curing the coating, and Matthews generally describes gloss control therefrom.
It also is known to cure the wearlayer by controlled exposure to ultraviolet radiation from commercially available mercury lamps. The mercury lamps, however, have a significant infrared component, which conveys excess heat to the curing substrate. If the wearlayer is coated on a rigid vinyl film and cured, excess heat causes a problem when the glass transition temperature of the vinyl film is exceeded. The excess heat causes distortion of the film and results in an unaesthetic appearance of the resultant floor covering product.